In this article, the highly destructive potential of global nuclear arsenals is reviewed with respect to nuclear force structures, evolution of nuclear capabilities, modernization programmes and nuclear war planning and operations. Specific nuclear forces data is presented for the United States, the Russian Federation, Great Britain, France, China, Pakistan, India, Israel and North Korea. Hypothetical, escalatory scenarios for the use of nuclear weapons are presented, including the calculated distribution of radioactive fallout. At more than seventy years since the atomic bombings of Hiroshima and Nagasaki and twenty-five years since the end of the Cold War, international progress on nuclear arms control and disarmament has now nearly stalled, with the emphasis shifting to modernizing and maintaining large inventories of nuclear weapons indefinitely. This perpetuates a grave risk to human health, civil society and the environment.